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Non-repeatable results still have importance

RESEARCH results do not always turn out as expected, but unexpected results are no less important, according to Danish researchers.

Take, for example, the case of researchers with Aarhus University in Denmark who said research results from South Korea led them to believe that a potato-derived product could be used to prevent diarrhea in piglets, thus avoiding the need for antibiotics. If successful, this would have been of significant benefit to the Danish swine industry.

However, the researchers said, even though the case had appeared to be promising, the results did not turn out the same. Potatoes produce defensive components called antimicrobial peptides (AMPs) to fight, for example, bacterial infections in the plant.

In a number of publications, a South Korean research group showed that there were large differences in the AMP contents of different species of potatoes and found one particular potato variety (Gogu Valley) with a much higher content.

"The South Koreans published some articles describing these fantastic results. They had made a product based on roughly purified potato protein from the promising variety that, in their experiments, suppressed pathogenic bacteria both in the laboratory and in pigs and poultry that were fed this potato protein," Aarhus associate professor Mette Krogh Larsen said.

On the basis of this research, the Aarhus researchers hypothesized that it would be possible to create a similar product to treat scours in piglets. Such a product could be made from the waste products in potato starch production and help reduce the use of antibiotics in pig production in Denmark.

The Danish scientists collaborated with potato starch manufacturer KMC and with potato breeding company LKF Vandel, the project leaders. The research behind the project was a combination of microbiology and food and protein chemistry and involved the university's departments of animal science and food science.

In the laboratory, the scientists investigated a number of potato clones and varieties that LKF Vandel made available. The aims were to identify potatoes with a high concentration of AMPs, to test these on Escherichia coli bacteria in the laboratory, to produce an effective potato protein extract to be tested in a pig herd and to optimize the content of the active compounds in the most promising potato varieties.

"If the theory could have been proved, we would have developed a health-promoting protein feed. (However,) we were simply not able to reproduce the results of the South Koreans," Larsen explained. "We even tried using the same potato variety that they had used. We were not able to source it directly from South Korea, but with many convolutions and efforts, we were able to import 5 kg of Gogu Valley potatoes from the U.S. Even in these, we were not able to detect any antimicrobial activity.

"No results are also a result. Now, we know that we need go no further along this track. We cannot rule out that the South Korean potatoes have been grown under different conditions that may have favored the production of AMP," Larsen added. However, "since we have not, at any time, found any significant antimicrobial effects in the laboratory, there is no reason to continue with the experiment on pigs. We can instead concentrate our efforts in other areas."

If the work on the fractionation and purification of potato proteins had continued, it is possible that some antimicrobial activity may have been detected. However, the researchers were not able to detect activity in any of the extracts or in the derived fractions produced in the pilot project.

Instead, the collaboration presented other opportunities in ongoing work with the fractionation of potato protein and its possible utilization in the food industry and has resulted in a new doctoral project that will begin soon.

Genomic selection

Improving animal welfare and farm income as well as reducing nutrient losses from pig production are some of the results expected from a five-year research project on genomic selection that just passed its halfway stage.

Aarhus researchers collaborated with the Pig Research Centre in Denmark to select pigs that can constitute the basis for breeding improvements that should ultimately benefit the pig industry. One of the methods used is genomic selection.

The project has so far focused on sows, and genomic selection has already been implemented in the breeding program for three pig breeds: Landrace, Yorkshire and Duroc. This is expected to increase the genetic gain in the traits under selection by about 15-25%.

The researchers are now focusing on slaughter pigs that are a three-way cross of the three breeds.

"Genomic selection will help improve the traits in finishing pigs that are directly related to production and meat quality. There will be a focus on improving meat quality through measurements of pH and boar taint in the carcass. Genetic improvements of these traits will increase the value of the carcass and result in less food wastage due to higher slaughter yield and less fat waste," explained Ole Fredslund Christensen, project leader and senior scientist at Aarhus.

The researchers will, among other things, develop methods that embody the so-called non-additive effects, such as hybrid vigor, that result in superior traits in crossbred offspring compared with the average of purebred offspring. If successful, genomic selection should result in further benefits.

Systematic crossings of the three pig breeds are underway, and genomic and phenotypic data have been collected, including data on mortality, growth and carcass quality -- the quality being meat content, pH and boar taint. Developing models that combine the genomic and phenotypic data is the next step in the project in order to form a number of strategies.

"We will develop strategies for the use of genomic selection that maximizes the marginal genomic improvement in the breeding programs for purebreds and for crossbreds while minimizing inbreeding in the populations as well as the implementation costs. The genetic gain is evaluated both in terms of financial profit and reductions in emissions of nutrients and carbon dioxide-equivalents," Christensen said, adding that the project will culminate in the practical implementation and testing of a prototype for genomic selection in pigs.

In addition to an expected reduction in nutrient emissions due to an improvement in feed efficiency of 0.02 feed units per kilogram of weight gained, the researchers also hope that the project will help reduce piglet mortality.

"The improvement in animal welfare is achieved through the incorporation of the maternal traits in the breeding program, which will result in better piglet survival in the nursing period. The effect is expected to increase survivability by 5% per year," Christensen explained.

It will take about five years for the changes in the breeding program to be reflected in the total pig production system, the announcement said. Production herds should see improvements within a year after improvements are observed in the breeding herds.

On-farm blending

Feedlogic Corp. has released results from a three-year trial that demonstrate the value of blending feed on the farm to more closely match the dietary requirements of the animals.

The trial was conducted at a 1,200-head commercial hog finishing site in Minnesota and showed a net improvement in profitability of more than $3.75 per marketed pig by blending feed versus feeding standard phase diets, an announcement said. The savings came primarily from a reduced feed cost per pound of gain.

More than 12,000 pigs were involved in the trial over a total of 10 turns of the site. The trial facility was set up with a FeedSaver blending system, which allowed half of the pigs (about 600 head) to be fed a set of standard phase diets and the other half to receive a blend of two standard diets -- typically the first and fourth diets used in the standard phase program.

Feed for both groups was weighed through the blending system, allowing an accurate comparison of feed consumption between the groups, the company explained, adding that the blended diets were changed with every 10 lb. per head of consumption, while the phase diets were changed as per the standard feed budgets.

Other standard protocols followed through the trial included:

* All pigs were placed at the same time and sorted evenly between pens (24 pens per group). The average weight of both groups was used as the starting weight for all pigs.

* Feed pricing was based on the average delivered cost of diets for each turn.

* Both groups were fed an identical diet with ractopamine for the last 14-21 days before marketing, as per the standard procedure in the producer's commercial system.

* Standard marketing procedures were followed, and the largest pigs from either group were shipped first. Pigs from each group were tattooed separately to allow tracking of carcass data by group.

According to the announcement, key results from the trial included:

* Feed conversion for the blend-fed group was 5% better than for the control group, at 2.56:1 versus 2.69:1.

* Blend-fed pigs had slightly better average daily gain, at 1.92 lb. per day, compared to the control group, at 1.89 lb. per day.

* Carcass yield, lean percentage and back-fat thickness were all virtually identical between the two groups.

* Feed cost averaged 27 cents/lb. of gain for the blend-fed group compared to 29 cents/lb. of gain for the control group.

The results of the trial confirmed previous theories that altering diets more frequently than the standard industry practice can improve feed conversion and lower the feed cost per pound of gain, Feedlogic said.

Aside from improving producer profitability, the blending concept demonstrated in the trial also can benefit feed mills since it reduces the number of diets that need to be manufactured and simplifies the feed delivery process, the company added.